For the lemon-garlic aioli: Combine the mayonnaise, lemon juice, pepper, salt and garlic in a medium bowl. Mix well, cover and refrigerate until ready to use.
For the maple-mustard slaw: In a large bowl, combine the mayonnaise, maple syrup, yellow mustard and Dijon mustard and mix well. Add the cabbage and toss to coat thoroughly. Season with salt. Cover and refrigerate until ready to use.
Finish the crab cakes: Form the crab mixture into eight 1-inch-thick patties. Heat the canola oil to 360 degrees F in a deep, heavy pot. Deep-fry the crab cakes until golden brown and just cooked through, about 3 minutes. (Alternatively, pan-fry the crab cakes in a skillet over medium heat, about 3 minutes per side.)
To serve: Spread the burger buns with lemon-garlic aioli. Set a crab cake on the bottom half of each bun, top with maple-mustard slaw and cover with the bun top.